This application claims the priority of Korean Patent Application No. 2003-101578, filed on Dec. 31, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to an information storage medium in which a nano-sized contact is formed between magnetic materials and an information recording and/or reproducing apparatus adopting the information storage medium.
2. Description of the Related Art
In an information reproduction method using magneto-resistance (MR), a MR head approaches a magnetic disc to detect variations in resistance of the MR head with respect to variations in magnetic field of the magnetic disc.
Giant MR (GMR) is known to exhibit a resistance variation of about 10% due to a variation in magnetic field. As an example, GMR is applied to a hard disc drive (HDD). As shown in FIG. 1, an information head 10 used in a GMR HDD has a structure in which lower and upper magnetic layers 12 and 14 are stacked on a substrate 11 and a non-magnetic layer 13 is interposed between the lower and upper magnetic layers 12 and 14. As shown in FIG. 2A, when the magnetization directions of the lower and upper magnetic layers 12 and 14 are parallel, the stack presents a low resistance. As shown in FIG. 2B, when the magnetization directions of the lower and upper magnetic layers 12 and 14 are anti(non)-parallel, the stack presents a high resistance. It is known that a GMR HDD reproduction head using a method of reproducing information depending on whether the magnetization directions of the lower and upper magnetic layers 12 and 14 are parallel or anti-parallel provides a recording density of about 100 Gb/in2.
Tunneling Magneto-Resistance (TMR) is mainly applied to a magnetic random access memory (MRAM), and exhibits a maximum resistance variation of about 50% and a recording density of about 300 Gb/in2.
An information storage medium, which is compact and contains a larger amount of information, is necessary for processing various kinds and enormous amounts of information. However, a GMR or TMR information reproduction method fails to satisfy the present technical requirements for such an information storage medium. Moreover, in the GMR or TMR information reproduction method, a metallic multi-layer thin film is used and has a complicated stack structure. Thus, there is a demand for a simple and high density information reproduction method and storage medium.